Abstract: A new high accurate azimuth and elevation angle estimation algorithm using ESPRIT algorithm is developed to avoid the ambiguous of extended aperture. Firstly the two-parallel-shape array geometry, which consists of sensors spaced much farther apart than a half-wavelength, is exploited to achieve array aperture extension, and the sensors are divided into 2 sub-arrays. The sub-array parallel with the x-axis is employed to extract low accurate but unambiguous y-axis direction cosines and high accurate but cyclically ambiguous x-axis direction cosines. Then, the sub-array parallel with the y-axis is employed to extract unambiguous x-axis direction cosines and cyclically ambiguous y-axis direction cosines. Finally, the low accurate unambiguous direction cosine estimates are used to resolve the cyclically ambiguous direction cosine estimates to obtain azimuth-elevation angle estimates. The proposed algorithm requires no 2D iterative searching, and thereby, offering high estimation precision with low computational complexity. Furthermore, a new pairing method based on the orthometric subspaces is proposed for the equivalent eigenvalues case. The simulation results indicate the performance of proposed algorithms.

Key words: radar engineering, array signal processing, ESPRIT, aperture extension, disambiguated